1. Technical Field of the Invention
The present invention relates to the storage and accessibility of information in multi-framed data transmission.
2. Background of the Invention
In multi-framed data transmission networks, such as Synchronous Optical Networking (SONET), Synchronous Digital Hierarchy (SDH) and Optical Transport Networking (OTN), the payload and overhead of data frames are transmitted through interleaving, with a portion of overhead being transmitted, then a portion of payload, then another portion of overhead, etc., until the entire frame has been transmitted. In both SONET and SDH the entire frame is transmitted in 125 microseconds; the SONET frame totals 810 octets in size, 27 octets of overhead with 783 octets of payload, while the SDH frame totals 2430 octets in size, 81 octets of overhead with 2349 octets of payload. OTN transmission is 4080 columns (bytes) by four rows. As part of data transmission, messages called trace messages are used to convey information from one Network Element (NE) to another. These messages are not transmitted at once; normally they are transmitted one byte at a time. Therefore, once data has been transmitted, an elastic store must hold the information until a decision is made regarding the next action. Often the data is held in registers, or a number of flip-flops, and depending on the presence of an alignment signal, such as the Multi-Frame Alignment Signal (MFAS) in OTN, the data can be associated with such alignment signal. However, other multi-framed data transmission networks, such as SONET or SDH, have no such multi-frame alignment signal, so the data can constantly rotate and change locations within the frame. In each case, the elastic store may be used to store information in the place of registers, as the elastic store may require less area in a chip than registers require. However, the use of an elastic store prevents the data contents from being directly addressable, and the data stored in the elastic store is not accessible by a microprocessor.